New changelog entries:
* debian/rsyslog.postinst: Make sure /var/log is owned by group syslog and
is group-writeable (LP: #1256695).
* Ensure that rsyslogd can create files in group adm, even when dropping
group privileges to syslog (LP: #484336):
- debian/patches/10-initgroups.patch: Try to set appropriate
supplementary groups before dropping UID.
- debian/rsyslog.postinst: Add syslog user to group adm.